The present invention relates to improvements in a control system for a continuously variable transmission (CVT) for a vehicle, and more particularly to a control system for a belt type CVT.
A Japanese Patent Provisional Publication No. 8-200461 discloses a typical belt type CVT which comprises driver and follower pulleys and a belt for intercoupling the pulleys. Each of the driver and follower pulleys has a variable groove at which the belt is held. A belt holding force for holding the belt by each pulley is varied basically to correspond with a line pressure which is produced from a fluid pressurized by a pump through an electrically controlled pressure control valve. The line pressure is increased according to the increase of an input load applied from an engine to the CVT. The input load is basically calculated from a throttle opening and an engine revolution speed of an engine.